An analysis of glomerular dynamics in rat, dog, and man

An analysis of glomerular dynamics in rat, dog, and man. A network thermodynamic model was utilized to assess similarities and dissimilarities in the predicted response of human, rat, and dog glomeruli to change in the independent variables regulating glomerular filtration. The analysis in rat and dog employed basal values reported in the micropuncture literature. The analysis in man was based on a calculated total nephron vascular resistance (RT) of 1.2 × 1010 dyne sec cm-5 with a range of pre- (RA) and postglomerular (RE) resistances and capillary hydraulic conductivities (Kf) that would provide a nephron blood flow (GBF) of ∼550 nl/min and single nephron filtration rate (SNGFR) of ∼65 nl/min. The maximal putative value for RA/RE in man was ∼1.1, a ratio demanding a Kf >20 nl/min mm Hg to obtain the required SNGFR. Solitary changes in RA and RE, glomerular capillary resistance, proximal tubule pressure, serum protein concentration, total vascular resistance, and Kf were induced and the resultant effect on SNGFR was examined in the three species. The relationship between changes in individual resistances, glomerular blood flow, glomerular filtration, and glomerular capillary pressure also was assessed. The patterns of response in man and dog, determined by the model, were remarkably similar and distinct from those of the rat in many regards. Except when the maximal possible RA/RE ratio is assumed for man, filtration pressure equilibrium was not found; plasma flow dependence of SNGFR was not evident in rat, dog, or man. The differences in SNGFR control predicted for the rat, on the one hand, and dog and man on the other may have distinct physiologic significance. Une analyse de la dynamique glomérulaire chez le rat, le chien, et l'homme. Un modèle thermodynamique en réseau a été utilisé pour préciser les similitudes et les différences de réponses prévisibles de glomérules d'homme, de rat et de chien à des modifications des variables indépendantes régulant la filtration glomérulaire. L'analyse chez le rat et le chien a utilisé les valeurs de base rapportées dans les études par microponction de la littérature. L'analyse chez l'homme était fondée sur une résistance vasculaire néphronique totale calculée (RT) de 1,2 × 1010 × dyne sec cm-5, avec une série de résistances pré (RA) et postglomérulaires (RE) et de conductivité hydraulique capillaire (Kf) donnant un débit sanguin néphronique (GBF) de ∼550 nl/mn et une filtration néphronique individuelle (SNGFR) de ∼